Inserts all data in the configuration files into the
database and destroys all old data, including the rows with
StorageType nonVolatile. The rows created from the
configuration file will have StorageType nonVolatile.

Thus, the data in the SNMP-COMMUNITY-MIB, after this
function has been called, is from the configuration files.

All snmp counters are set to zero.

If an error is found in the configuration file, it is
reported using the function config_err/2 of the error report
module, and the function fails with reason
configuration_error.

ConfDir is a string which points to the directory
where the configuration files are found.